The ability to fabricate analytical devices at micrometer and nanometer scales has enabled measurement and monitoring of many physical, chemical and biological parameters unobtrusively, inexpensively and with great accuracy, e.g. Grayson et al, Proceedings IEEE, 92(1): 6-21 (2004); Schumacher et al, Lab Chip, 12(3): 464-473 (2012); and the like. Such devices may be fabricated in wide variety of substrate materials (referred to herein as microelectromechanical system materials, or “MEMS materials”) which are typically selected on the basis of application-specific requirements, such as, chemical inertness, strength, rigidity, conductive or insulation properties, temperature sensitivity, ease and expense of fabrication, and the like. In analytical devices where optically based sensing or manipulation is employed, the absence of, or at least the controllability of, optical activity in substrate materials is important.
Optical detection of nucleotides has been proposed as a potential solution to some of the technical difficulties in the field of nanopore sequencing, e.g. Huber, International patent publication WO 2011/040996; Russell, U.S. Pat. No. 6,528,258; Pittaro, U.S. patent publication 2005/0095599; McNally et al, Nano Lett., 10: 2237-2244 (2010); and the like. Nanopore sequencing relies heavily on the use of micro- and nanofabricated MEMS materials, whether nucleotide detection is optically based or current based. Unfortunately, although many MEMS materials meet chemical, strength, rigidity and other requirements for nanopore sequencing and other analytical processes, they may be optically active. That is, they may generate a high level of background fluorescence that obscures the very low level high frequency fluorescent signals characteristic of optically based nanopore sequencing and other optically based measurements.
In view of the above, it would be advantageous to analytical devices comprising MEMS materials and optical detection systems, such as nanopore sequencing devices, if there was a method available for reducing or eliminating their optical activity, such as the undesired generation of background fluorescence.